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It can apply to any media, yes (Hence One Work Wonder as a redirect name), but your example is more a Creator's Oddball because he was still composing music, just a different sort. (Compare Beethoven composing a single opera)
I think this example is enough of a detour to also count as They Also Did, which can overlap with One Work Wonder or Creator's Oddball but can also be an ongoing second field of work. A personal favorite example is Beatrix Potter, a brilliant mycologist who also wrote and illustrated some children's books.
Does this trope apply if someone has a work in a major field? Denny Zeitlin is a renowned jazz composer, but Invasion of the Body Snatchers is the only film score he did. Does that fit?